A TPC FOR THE INTERNATIONAL LINEAR COLLIDER Paul

A TPC FOR THE INTERNATIONAL LINEAR COLLIDER Paul Colas, on behalf of the LCTPC collaboration

28/02/2017 Paul Colas - A TPC for ILC - INSTR 17 2 The ILC and the ILD detector A superconducting linear e+e- collider, 31 km long, starting at √s=240 Ge. V, upgradable to 350 (ttbar), 500+ (3 H coupling) and 1000 Ge. V (max. energy). Siting studies well advanced at Ichinoseki, Iwate pref. , Japan The ILD concept comprises : A highly segmented calorimeter A tracker combining Silicon detectors and a large TPC A pixellized vertex detector Jet measurement relies on the ‘Particle Flow’ concept The ILD collaboration has been building its organization in the last two years (spokesperson, Institute Assembly, Executive team, Technical team

28/02/2017 Paul Colas - A TPC for ILC - INSTR 17 3 The ILD TPC Calibration/alignment The required precision on the sagitta (10 µm) imposes a severe limitation on the systematics (22 µm internal, 10 µm TPC wrt other trackers) All handles will be considered for alignement: - Survey, Laser tracks, Laser photo-electric effect on dots on the cathode - Studies B on and off - V 0 mass, tracks, etc. .

28/02/2017 Paul Colas - A TPC for ILC - INSTR 17 4 The LCTPC collaboration and the DESY test setup All the TPC R&D is gathered. www. lctpc. org The collaboration shares a test facility (Field cage, magnet, endplate, cosmic-ray trigger, ancillaries) Allows testing/comparing several technologies/ideas with cost-awareness

28/02/2017 Paul Colas - A TPC for ILC - INSTR 17 5 Technologies under study MPGDs suffer less from Ex. B effects than MWPCs. They require less heavy mechanics. Panels with each technology have been made and tested. European GEMs Micromegas Standard kapton triple GEM with ceramic spacers Mesh on top of a charge-dispersing resistive anode Grid. Pix Asian GEMs Integrated grid on 55 µ digital pixels

28/02/2017 Paul Colas - A TPC for ILC - INSTR 17 6 Micromegas with charge dispersion Fully integrated design : 0. 25 X 0

28/02/2017 Paul Colas - A TPC for ILC - INSTR 17 7 Micromegas with charge dispersion

28/02/2017 Paul Colas - A TPC for ILC - INSTR 17 8 Eu GEM modules : flatness improved Quality control: foil flatness GEM stack of 2 modules measured Last generation height RMS: 50 -90μm new RMS: 30 -50μm → New generation consistently more flat by almost a factor of two CURRENT PREVIOUS Calculated gain fluctuation for triple GEM stacks: 6. 1% → 4. 2%

28/02/2017 Paul Colas - A TPC for ILC - INSTR 17 Gridpix : ‘digital TPC’ • Reconstruct every ionization electron with a high efficiency. Measure d. E/dx by cluster counting Recently progress has been done with Timepix 3 and chip protection against sparks has been improved. 9

28/02/2017 Paul Colas - A TPC for ILC - INSTR 17 Results on resolution All pad TPC technologies give similar results (but with 3 mm pads for MM and 1. 2 mm pads for GEMs) 10

28/02/2017 Paul Colas - A TPC for ILC - INSTR 17 Results on resolution All pad TPC technologies give similar results (but with 3 mm pads for MM and 1. 2 mm pads for GEMs) 11

28/02/2017 Paul Colas - A TPC for ILC - INSTR 17 For the Eu GEMs, it has been checked that minimizing the ion backflow does not worsen the resolution. 12

28/02/2017 Paul Colas - A TPC for ILC - INSTR 17 13 Distortions Module frames at ground while the top GEM or Micromesh is at HV induces distortions at the level of O(1 mm). New design should suppress this effect. Eu GEM Micromegas

28/02/2017 2 PCO 2 cooling High latent heat, high specific heat: 10 °C at 50 bar (0. 8 mm pipes) Tested in 2014 and 2015 in test beam. Paul Colas - A TPC for ILC - INSTR 17 14

28/02/2017 Paul Colas - A TPC for ILC - INSTR 17 15 Need for gating In TPCs, ions are produced and migrate very slowly (1 m/s). They produce a charge density which can be one or two orders of magnitude above the primary ionization (IBF*Gain). The resulting electric field can be the origin of distortions. At the ILC, the bunch trains last about 1 ms every 200 ms, giving rise to ion disks slowly drifting to the cathode

28/02/2017 Paul Colas - A TPC for ILC - INSTR 17 16 Need for gating In TPCs, ions are produced and migrate very slowly (1 m/s). They produce a charge density which can be one or two orders of magnitude above the primary ionization (IBF*Gain). The resulting electric field can be the origin of distortions. At the ILC, the bunch trains last about 1 ms every 200 ms, giving rise to ion disks slowly drifting to the cathode After 2 disks, the electrons receive a kick of up to 60 µm, too much wrt the systematics

28/02/2017 Gating options The ions must be stopped before penetrating too much the drift region. The device to stop them must be transparent to electrons. Here is the example of a highly transparent wire mesh used to create a counter field near the amplification device Paul Colas - A TPC for ILC - INSTR 17

28/02/2017 Gating options The ions must be stopped before penetrating too much the drift region. The device to stop them must be transparent to electrons. Here is the example of a GEM with a Delta V polarization. Paul Colas - A TPC for ILC - INSTR 17 18

28/02/2017 Paul Colas - A TPC for ILC - INSTR 17 19 GEM gating – Large aperture GEM transparency

28/02/2017 Paul Colas - A TPC for ILC - INSTR 17 20

28/02/2017 Paul Colas - A TPC for ILC - INSTR 17 21 Test beam results with a gating GEM • A module with a gating GEM has also been tested in beam in November 2016. The results are consistent with no more degradation than expected (~10%) • The analysis is still in progress, but GEM gating seems to be a possible solution for the gating at ILC

28/02/2017 Paul Colas - A TPC for ILC - INSTR 17 Prospects • A slide of my talk from February 2014 at INSTR… 22

28/02/2017 Paul Colas - A TPC for ILC - INSTR 17 23 Toward the Final Design of ILD TPC The earliest timeline? 2014 -15 2015 -17 2017 R&D on ion gates and a decision on the ion gate: Beam tests of new LP modules with the gate Prioritization of the MPGD technology and module ILC LAB & ILD detector proposal 2017 -19 tests Final design of the readout electronics for ILD TPC and its 2018 -19 Design of ILD TPC TDR for the ILD tracking system: 2019 -23 Prototyping and production: Electronics (chips boards) Prototyping and production: Modules Production: Field cage/endplate and all others 2024 -25 TPC integration and test 2026 2027 TPC Installation into the ILD detector ILC commissioning

28/02/2017 Paul Colas - A TPC for ILC - INSTR 17 24 Prospects • After 3 years, the goals have been attained and the expectations for the timeline are still valid. • This is true, however, in the new context of a staged ILC with cost reductions. • In conclusion, most of basic questions and a large part of engineering questions have been answered for all technologies, matching the ILC requirements. We expect a timely decision to build the ILC.